Blockage of human arteries is a widespread malady and, as such, represents a significant health concern. Blockages reducing blood flow through the coronary arteries to the heart can cause heart attacks, while blockages reducing blood flow through the arteries to the brain can cause strokes. Similarly, arterial blockages reducing blood flow through arteries to other parts of the body can produce grave consequences in an affected organ or limb.
The build-up of atherosclerotic plaque is a chief cause of blockages, termed stenoses, which reduce blood flow through the arteries. Consequently, several methods have been introduced to alleviate the effects of plaque build-up in restricting the artery. One such method is a procedure termed angioplasty, which uses an inflatable device positioned at the stenosis to dilate the artery. A typical angioplasty device is disclosed in U.S. Pat. No. 4,896,669 to Bhate et al. The angioplasty device of Bhate et al. includes an inflatable balloon which is attached to the distal end of a hollow catheter tube. The proximal end of the catheter tube is attached to a fluid source.
To treat an arterial stenosis, the balloon of Bhate et al. is introduced into the artery in a deflated state and guided through the artery over a guide wire to a position adjacent the stenosis. Fluid from the fluid source is then infused into the balloon via the catheter tube to inflate the balloon. As the balloon expands, it presses against the arterial wall in the region of the stenosis, dilating the artery at the stenosis and restoring it to a sufficient size for adequate blood flow therethrough. The balloon is then deflated and removed from the artery, thereby completing the treatment. Sometimes, the effectiveness of this treatment is limited, because the stenotic tissue is left essentially intact.
Another method is disclosed in U.S. Pat. No. 4,273,128 to Lary. In the Lary method, a combination balloon and surgical knife assembly is inserted into the blood vessel and advanced to the stenosis. The knife blade is then forced through the stenotic tissue, followed by expansion and advancement of the balloon to dilate the vessel. As this method involves advancement of a sharp surgical blade through the vessel, care must be taken to avoid damage to vessel walls or perforation of the epicardium.
It has been found that dilatation of the stenotic segment of a blood vessel is facilitated by incision of the stenotic tissue, either before or during expansion of the dilating balloon. The methods heretofore known fail to perform this function without some serious drawbacks. Therefore, it is an object of the present invention to provide a method and apparatus for dilatation of a stenotic segment using a combination balloon and cutting device which has minimal risk of damaging surrounding tissues. It is also an object of the present invention to provide a method and apparatus for dilatation of a stenotic segment using oscillatory motion to assist in incision of the stenotic tissue before dilatation of the segment. It is a further object of the present invention to provide a method and apparatus for dilatation of a stenotic segment using oscillatory motion to assist in incision of the stenotic tissue during dilatation of the segment. Still another object of this invention is to provide an effective apparatus for dilatation of a stenotic segment using oscillatory motion, which is relatively inexpensive to manufacture and easy to operate.